During the operation of an internal combustion engine, it is desirable to acquire temperature data at various locations within one of the pistons during different engine loading conditions. To collect these data, one or more through passages or bores are drilled into the piston from the top surface of the crown to the bottom surface of the crown or the undercrown, or, alternatively, through the sidewall into a cooling gallery or the bottom surface of the crown. Thermocouples are inserted into the through passages or bores, and the space above the thermocouple, as well as the space behind the thermocouple, is filled with heat resistant material to prevent damage to the thermocouple. Alternatively, the space above the thermocouple may be tapped to receive a metal screw.
There are many locations within the piston for which temperature data is desirable, but drilling the through passage or bore for the thermocouple is simply not possible due to various physical constraints. Furthermore, the location of the thermocouple is known only to a certain spatial precision, which may not satisfy the accuracy requirements of computer-based piston and/or engine modeling tools. When accurate thermocouple locations need to be determined, the piston is destructively sectioned after the testing is completed in order to measure the precise location of the thermocouple in relation to the crown, sidewalls and undercrown of the piston. Accordingly, computer-based piston and/or engine modeling can only be accomplished after the precise location of the thermocouples are determined through destructive means, after which further testing of that piston is no longer possible.
It is therefore desirable to accurately and non-destructively locate thermocouples and/or other sensors within a piston at any desired location, with a much higher degree of precision, than has previously been possible.